1. Field of the Invention
The present invention relates to a data input-output control apparatus that receives data arriving over an input bus and outputs the data to an output bus with a larger bus width than the input bus.
2. Description of the Related Art
To increase data throughput, it is common practice to use an output bus with a larger bus width in system controllers that transfer data using a bus (such as the one disclosed in Japanese Patent Application Laid-open No. H08-63429). As a result, often disparity is seen in the bus widths of an input bus over which data is received and the output bus. Such a system controller, which transfers data from a smaller input bus to a larger output bus, changes the format of the data input over the input bus to a format that matches the larger output bus. In other words, the system controller buffers data input over the input bus until enough data suitable for the format matching the output bus accumulates and then transfers the data to the output bus.
However, in the technology described above, as transfer of data is held up until enough data suitable for the format matching the output bus accumulates, an adverse effect can be seen on the latency due to the data not accumulating fast enough when there is no data congestion.